The present invention relates to a substrate processing apparatus, in particular, relates to a substrate processing apparatus for forming a film on a substrate surface to be processed.
As one example of this type of a substrate processing apparatus, there has been known an apparatus for forming a film on a surface to be processed, by accommodating a substrate in a processing chamber, and rotating the substrate thereof, and by supplying the desired processing gas toward the substrate surface to be processed. In the said apparatus, there is installed a gas supply unit for supplying desired processing gas in a direction parallel to the substrate surface to be processed, and the processing gas is designed to be supplied from the gas supply unit toward the substrate surface to be processed.
It should be noted that, as prior documents thereof, JP-A-2000-182979, and JP-A-11-102903 are included.
In this case, there were such cases, in some times, that film thickness decreased at the center part of the substrate, and thickness of a film formed on the substrate surface to be processed did not become uniform over the whole surface to be processed. That is, in a substrate processing apparatus such as a CVD (chemical vapor deposition) apparatus, it is configured so that processing gas is flowed horizontally to a wafer, however, in a processing chamber of a normal-flow system, where an exhaust port is arranged at the lower end part, because of arrangement of a gas nozzle at the inside of a process tube, a space between the wafer and the process tube becomes wider to a wafer pitch, resulting in flow-out of most of the processing gas through the space between the wafer and the process tube, which raised a problem that a supply of processing gas toward the wafer center was insufficient, in particular, at the top side (upper end side) of a boat and provided such film thickness distribution in a surface as thicker at the circumference part and thinner at the center part.
In addition, in a processing chamber of a side-flow system, such as described in patent application 2007-165388, having a gas nozzle provided with a plurality of gas supply holes extending in a lamination direction of a substrate, which is a gas supply unit installed in a processing chamber, and a plurality of gas exhaust holes installed at a position facing this gas nozzle, as shown schematically in FIG. 4, a gas supply port 700 and an exhaust port 704 are arranged in facing positions in each wafer 701. Therefore, in the case where gas is supplied without rotation of the wafer 701, as shown in FIG. 4(a), film thickness becomes thinnest at a position a little displaced toward the exhaust port 704 side from the center of the wafer 701; on the other hand, in the case where the wafer is rotated, as shown in FIG. 4(b), a W-character-type film thickness distribution is obtained, therefore, to enhance uniformity, it is necessary to promote a gas consumption not only at the end of the wafer 701 but also at the center part thereof. Here, in FIG. 5, experimental data of film thickness distribution was shown, in the case where gas is supplied by rotation of the wafer 701, under film-formation condition of a temperature of 220° C. and a phase flow amount of 15 slm, in a processing chamber of a side-flow system.
Accordingly, it is a main object of the present invention to provide a substrate processing apparatus that is capable of making uniform thickness of a film formed on a substrate surface to be processed.